Critics of the decision have warned it could undermine Switzerland’s political system, paving the way for frivolous appeals against referendums. The nationalist Swiss People’s Party (SVP) branded the Federal Supreme Court ruling “extremely controversial” and said the judges had also based their final decision on false figures. An SVP spokesman said judges will be able to review “false” arguments in the future and “thus undermine direct democracy”.
Free Democratic Party national council spokesman Hans-Peter Portmann said it had been a “hard decision” and feared it could lead to a “new practice” for some other referendums.
The referendum, held in February 2016, asked voters if married couples and co-habiting partners should pay the same tax.
Voters rejected the proposal, with 50.8 percent against and 49.2 percent in favour.
But the supreme court has now voided the result on the grounds that voters were not given full information, and the vote must be re-run.
During the referendum campaign, the Swiss government told voters just 80,000 of married couples were paying more tax than couples living together but later admitted the true figure was almost half a million.
The court ruling said: ”Keeping in mind the close result and the severe nature of the irregularities, it is possible that the outcome of the ballot could have been different.”
The Christian Democratic Party (CVP), which lodged an appeal against the result in June 2018, welcoming the court’s decision as a “boost for the political rights of Swiss voters”.
CVP President Gerhard Pfister was relieved about the annulment, saying it was not least about “the restoration of confidence in the Bundesrat”.
Mr Pfistyer said the court had decided the information in the voting book was “blatantly wrong” and that parliament and voters had based their decisions on false figures.
Under the Swiss system of direct democracy, a proposal needs 100,000 signatures before going to a referendum.